Field of the Invention
The invention generally relates to magnetic alloy non-rare earth nanoparticles, magnets made therefrom, and methods of making the same. In particular, the non-rare earth magnetic nanoparticles are single phase materials and are made using a continuous flow process.
Background of the Invention
Permanent magnets (PMs), specifically those containing rare earth metals, are an indispensible component of many applications in electric, electronics, communications, and automobile industries. The emergence of green technology markets such as plug-in hybrid/electric vehicles (e.g. PHEVs and EVs), direct drive wind turbine power systems, and energy storage systems (e.g. flywheels) has created an increased demand for PMs, since they produce high torque with a much smaller motor.
The majority of the cost for producing electric motors is directly related to the magnetic materials used therein, particularly the rare earth metals that are currently used to produce PMs. Unfortunately, recent market trends have made the production and procurement of rare earth permanent magnets more challenging and less cost efficient. The lack of a secure supply chain for rare earth metals makes them very expensive. If electric motors are to achieve prominent integration into green technologies and be affordable for the average consumer, it will be essential to reduce the cost of the materials. Unfortunately, there are currently no existing alternatives to rare earth metals for producing energetically equivalent PMs. There is thus a pressing need in the art to identify new materials to replace rare earth metals in the manufacture of PMs, as well as efficient, cost effective methods of manufacturing PMs using such materials.
The production of non-rare earth cobalt magnetic nanoparticles using a wet chemical polyol process has been described, e.g. see published United States patent application 2012/0168670 (Harris), the entire contents of which is hereby incorporated by reference. However, this publication describes only a mixture or admixture of magnetic Co2C and Co3C phase cobalt carbides nanoparticles and a method for the scalable manufacturing of those particles.
U.S. Pat. Nos. 5,783,263; 5,549,973; and 5,456,986 (Majetich et al., the entire contents of each of which is hereby incorporated by reference) describe metal carbide nanoparticles. However, the particles are coated and their manufacture is tied exclusively to a particular process that involves preparing graphite rods which are packed with a magnetic metal oxide.
The prior art has thus far failed to provide alloy non-rare earth nanoparticles and methods to make the same in quantities sufficient to be practical for manufacturing purposes.